Titanium Trisulfide Nanoribbons Affect the Downy Birch and Poplar × Aspen Hybrid in Plant Tissue Culture via the Emission of Hydrogen Sulfide

Plant tissue culture is an important tool for accelerated vegetative reproduction of woody plants. To increase the efficiency of this method, it is necessary to search for new growth stimulators and protectors of microshoots. Two-dimensional (2D) nanomaterials are highly promising for applications in medicine and biotechnologies. We have studied the effects of TiS3 nanoribbons with the following mean dimensions: thickness less than 100 nm, length 1–10 μm and width 0.4–1 μm upon poplar × aspen hybrid and downy birch microclones in plant tissue culture. We have found the effectiveness of this particular nanomaterial as a sterilizing and stimulating agent in the initial growth stage and as a rhizogenesis-activating agent in the rooting stage. We analyzed a wide range of TiS3 concentrations in the nutrient media and identified 1.5 and 3 μg/L as optimal. However, concentration-dependent toxic effects manifesting themselves through microclones viability suppression have been discovered in the groups exposed to 6 and 15 μg/L TiS3. We have established that plant reaction to TiS3 treatment is specific for different plant species, i.e., downy birch is generally more tolerant than poplar × aspen hybrid. Here, we propose that the protective and stimulating effects of titanium trisulfide as well as its toxicity in high concentrations can be explained by the release of hydrogen sulfide as a result of aqueous hydrolysis of nanoribbons and its effect on plants. Additional studies are required in order to assess all biological effects produced by TiS3 nanoribbons at further stages of ontogenetic development and to identify the mechanisms of their action.